[EdHolland]

On the "do not touch" trimmers, it was as I suspected, they are for compensating the antenna tuning circuits on broadcast, and shortwave (one for each).

Guessing now, but I imagine the factory setting procedure established a compromise to level up the set's sensitivity across the multiple bands. These trimmers would not affect the position of stations on the dial. However, adjusting them for a peak on one band or dial setting might come at the cost of low sensitivity on another.

My 16X seems to tune with good sensitivity across the bands, just by following the standard alignment procedures. Shortwave requires a reasonable amount of antenna, and good conditions. Above ~10 Megahertz can be poor at the moment on any radio ancient or modern, as we are at a low point in the sunspot cycle. IT should be possible to pick up stations on the broadcast/lowest shortwave band, and tuning up around 3.5 MHz you may well encounter some ham radio traffic. I mention this, because there are quite a few operators using vintage gear and AM output, so it is easy to listen with our old radios. Their signal quality is often excellent, and shows off the audio capability of the Philco.